Brain swelling, or encephalitis, is often the result of brain injury, infection, or other malady. As the brain swells, it compresses the surrounding intracranial fluid, increasing intracranial pressure and the pressure on the brain. The condition known as congenital hydrocephalus, commonly referred to as “water on the brain,” is a disorder that can result in permanently elevated intracranial pressure (ICP), requiring long-term treatment. Unfortunately, excess ICP can damage the brain physically and can reduce blood flow to the brain causing oxygen deprivation and possible death to brain tissue. This secondary type of brain injury can be more extensive than the original injury to the brain (e.g., from a head trauma).
As a result, it can be beneficial to monitor ICP for several hours or days after a head injury to ensure the brain edema subsides and to prevent further injury. In the congenital case, ICP monitoring maybe required for a lifetime. Fortunately, this overpressure situation can often be reduced, or eliminated, by simply draining a portion of the cerebral fluid out of the skull. The fluid can be drained externally, or can be transported to another part of the body for reabsorption (e.g., into the abdominal cavity).
In either case, an intracranial catheter inserted into the skull connected to a shunt can provide ICP drainage. The catheter can be completely internal or partially external to the patient's body. As shown in FIG. 1, for ICP control, for example, the catheter 105 can be implanted into the intracranial cavity (ICC) 135 through a burr hole 120 in the skull 110. For long term use, the catheter 105 can be implanted under the patient's scalp 130, for example, and drain into an internal body cavity (e.g., the abdomen) for reabsorption/removal by the body.
Because at least a portion, if not all, of the catheter 105 is implanted, detection of blockages, or occlusions, is difficult. This problem is exacerbated somewhat in the case of intracranial fluid (ICF) because ICF is also clear. This makes external detection using video imaging, for example, more difficult.
In addition, after detection, removing the occlusion using conventional techniques is difficult. One method for removal of occlusions is explantation of the catheter. In other words, the catheter is removed from the patient's body and then cleaned or replaced. This method is time consuming and requires hospital resources (e.g., operating rooms, staff, etc.). This method also represents obvious risks of infection and injury to the patient, particularly intracranial applications where brain damage is possible.
Another method is to insert a tool into the catheter to clear the blockage. This may be achieved using simple mechanical tools, such as using a balloon catheter, to dislodge and/or remove material. When using this technique, however, material removed during the process can become dislodged and travel through the patient's body only to cause a blockage elsewhere. This can result in serious complications. If this results in an arterial blockage and a loss of blood flow to the brain, for example, stroke can result.
Yet another method is the insertion of a probe into the catheter to provide some sort of electromagnetic energy to the blockage site. Radio-frequency (RF) or laser energy, for example, can excite the cells forming the blockage to the point of evaporation. This can enable the blockage to be removed, but also presents a risk of injury to the patient as the probe is manipulated to the blockage site. In addition, improper manipulation of the probe can result in unintended damage to the catheter and surrounding, healthy tissue.
What is needed, therefore, is a catheter system with built-in detection and clearing of occlusions. The catheter should provide external detection of occlusions with minimal intrusion. The catheter should also provide one or more internal means for occlusion removal without catheter explantation. The catheter should also preclude the use of external tools for occlusion removal. It is to such a system that examples of the present invention are primarily directed.